U.S. Pat. No. 6,723,079 and EP-A-1348412 describe controlled discharge ostomy devices including an inflatable membrane seal for creating a temporary conformal closure of the stoma. The inflatable seal comprises a sealed chamber having an inflation port closed by a check valve. After having fitted the appliance at a stoma, the seal is inflated by coupling an external inflation source, for example a pump or a syringe, to the check valve. Once the inflation fluid has been injected into the chamber, the check valve seals the chamber preventing loss of inflation fluid and preserving the inflation state.
Such a system can be comfortable to fit and provide good seal performance, but may require careful design. One design issue is the provision of an external inflation source as a separate item carried by the user, in order to be able to inflate the seal after having fitted the appliance, or to top-up the seal with additional inflation fluid in case of fluid loss or stoma leakage. Another design issue is the importance of keeping the contact pressure between the stoma and the membrane seal in a narrow range, namely as low as possible (to ensure good blood perfusion in the stoma tissue) while maintaining an effective temporary seal against discharge of stool. However, it is difficult to keep the contact pressure in such a narrow range because, for a given amount of inflation fluid in the chamber, any change in chamber volume caused by movement of stoma, directly affects the inflation pressure. During the wear time of an ostomy appliance, the stoma can move dynamically inwardly towards the body and/or outwardly away from the surface of the peristomal skin over a total distance that can exceed 1 cm. This movement can be due to peristaltic motion of the bowel, impending release of stool or gas from the stoma, or muscular contractions of the abdomen. Under conditions when the stoma moves inwardly towards the body (i.e. increasing the volume of the inflation chamber), the contact pressure between the membrane seal and the stoma can fall, increasing the risk of leakage of stool if the contact pressure is too low. In contrast, under conditions when the stoma or its contents pushes outwardly against the membrane seal (reducing the volume of the inflation chamber), contact pressure between the seal and the stoma can potentially rise. During such times, the increased contact pressure may result in undesirable reduced blood perfusion in the stoma. The duration of such conditions may be highly unpredictable, some lasting only seconds, others minutes, and sometimes several hours.
International patent application publication no. WO 2009/029610 describes an alternative seal that is both self-compensating and self-urging towards the stoma. The seal comprises a fluid chamber including a fluid impermeable membrane that forms a movable wall of the fluid chamber, one or more fluid flow regulation ports communicating with the chamber; and resilient foam disposed within the fluid chamber. With such a seal, the contact pressure between the seal and the stoma has both a static component and a dynamic component. The static component comes from the foam, which is compressed by the seal bearing on the stoma, and applies a resilient return force on the stoma. The foam is configured so that the static component of the contact pressure is always within the narrow range of acceptability explained above. The dynamic component of the contact pressure results from the port regulating fluid flow to and from the chamber, as the chamber volume adapts to follow any movement of the stoma. The port defines a dynamic damping characteristic of adaptation of the seal, in addition to the effect of the foam.
Such a self-urging design has the potential advantage that no external inflation source is needed, thereby avoiding the user having to carry such a separate device. The pressure inside the seal is self-regulating, and the seal can adapt to different volumes automatically. While the foam permits a wide range of stoma shapes and sizes to be accommodated, the dynamic damping characteristic resists compression of the seal should the stoma begin to push outwardly. The fluid trapped in the chamber by the damping characteristic generates a temporary, dynamic increase in the contact pressure exerted by the seal to counter such a challenge from the stoma. A transient challenge may be caused by stool and flatus in the stoma, and the temporary increase in sealing pressure enhances the seal against escape of stool, without the increased sealing pressure being exerted for too long to obstruct regular blood perfusion of the stoma. The damping characteristic only temporarily traps inflation fluid, thereby allowing the seal to adapt in volume if the outward movement of the stoma is more than transient.
US-A-2007/088300 describes a single-use ostomy appliance including an ostomy coupling for releasably coupling first and second portions at a stomal orifice. The two portions may be separable body-side and non-body-side parts, or the two portions may be portions of a unitary ostomy device such as a controlled evacuation device. The coupling includes a mechanical fastener configured such that the coupling is rendered substantially not resecurable after the fastener is released.
US-A-2007/129695 describes an ostomy coupling including a body-side coupling member, an appliance-side coupling member including plural fastener lugs, and a bracing member. The lugs flex independently of each other to provide plural independent latching fastenings. The bracing member is moved between a bracing position in which the bracing member locks the lugs by resisting flexing movement, and a non-bracing or dis-mounted position in which the lugs are free to flex. The ostomy coupling is used with an ostomy pouch or with a controlled discharge ostomy appliance.
The present invention seeks to further enhance versatility and ease of use of controlled discharge ostomy appliances.